Part of the effort is devoted to the chemistry of dinitrogen complexes of osmium(II) ammines. Such complexes can be formed in aqueous solution from elementary N2, even though Os(NH3)5OH2 2 plus is so strongly reducing that it is formed from Os(III) in the presence of a reducing agent only at a low steady state concentration. A binuclear complex is also formed which is most stable in the mixed (2.3) oxidation state. The principle effort in osmium-dinitrogen chemistry will be devoted to preparing such binuclear complexes which include also chloride ion in the coordination sphere. The rationale of this effort is to stabilize the Os-N2 bond in a species such as Os(III)-N triple bond N-Os(III) sufficiently to investigate the possibility of N triple bond N bond rupture to form nitrido complexes of Os(VI). Other work is directed to preparing new complexes of molybdenum in low oxidation states (2 plus or 3 plus) in combination with sulfur-containing ligands. The species Mo sub 2 super 4 plus is being used as a starting material. It is expected that Mo sub 2 super 4 plus or Mo (III) in the presence of ligands such as RSH will be strong, multi-electron reducing agents, and the action of such reagents on N2 and other inert oxidizing agents will be studied.